Control means for portable electric tools



''May 4, 194's.

R. HAPPE 2,441,096

CONTROL MEANS FOR PORTABLE ELECTRIC TOOLS Filed Spt. 4, 1944 i g mINVENTOR ATTORNEY Patented lflpy 4, 1948 CONTROL 8 FOR-PORTABLE ELECTRICTOOLS Reynold Happe, Plttstown, N. 1., assignorto The Sin gerManufacturin Company, Elizabeth,

- N. 1., a corporation of New Jersey Application September 4, 1944,Serial No. 552,589

10 Claims. (01. 200-157) This invention relates to portable electrictools and, more particularly, to the switch mechanism thereof. It hasfor its primary object a switch mechanism of simple and effectiveconstruction,

automatic in operation in the sense of requiring no special manipulationby the operator to effect the openingand closing of the switch at timesappropriate to the work in hand, and capable of organization as aconvenient unit for'ready installation in the handle of any particulartool.

With the above and other objects in view, as will hereinafter appear,the invention comprises the devices, combinations and arrangements ofparts hereinafter set forth and illustrated in the accompanying drawingsof a preferred embodiment of the invention, from which the severalfeatures of the invention and the advantages attained thereby'will bereadily understood by those skilled inthe art. 1

In the drawings:

Fig. 1 is a broken-out sectional view illustrating the preferred form ofswitch mechanism installed in the handle of a portable electric tool.

Fig. 2' is a somewhat diagramamtic, sectional view, with parts brokenout, to illustrate the functioning of the switch. v

Fig. 3 is a section on the line 3,3 of Fig. 1.

Fig. 4 is a perspective view of the switch contacts and associatedelements.

Fig. 5 is a perspective view of a switch actuating element and itssupporting stud.

Referring to the drawings, the rearend IU of the housing of a portableelectric-tool, such as a drill, is shown as terminating in a pistol griphandle ll of generally hollow construction and partially open at therear. The handle is closed at the bottom by a butt plate I2 on the innerface of which is anchored the current-supply cable l3. The current leadspass from this point to the switch unit and thence to the motor mountedin housing l0.

- bodily insertable into the handle ll through the opening in the rearthereof. The switch unit is adapted to be secured to the handle byscrews l8. Within .the housing 20 is a snap-switch of any suitableconstruction. As illustrated, it comprises two sets of stationary,spring contacts 22 and 23 the adjacent, free ends of which are separatedby a sliding contact member 25 consisting of a block of insulatingmaterial carrying the contact pieces 26. The contacts 22 are connectedrespectively to the leads I9 from cable i3, and the contacts 23 carrycontact buttons 24 adapted toensa e the springcontacts it when the unitis inserted into the handle, as above stated. The sliding movement ofcontact member 25 may be limited as by stops 46 (Fig. 2). In the upperposition of the contact member 25 the circuit is broken. In the lowerposition of the contact member the circuit is closed by the contactpieces 26 respectively bridging pairs of contacts 22 and 23.

Movement of the sliding contact member 25 is eiTected by a snap-actionspring 28 adapted to be thrown from the Fig. 2 (open-circuit) position,

through dead-center, to a closed circuit position represented by thedash-and-dot line designated 40. As indicated, one end of the spring 28engages a lug 21 projecting from sliding contact member 25, and theother end of the spring surrounds a pin '29 projecting from an actuator3|, the sliding movements of which eifect the throwing of thesnap-spring 28.

The upper end of actuator 3| is provided with bent up, spaced, wingportions 34. As shown in The rear bearing of the motor shaftis mountedin a support ll carried by the frame of the motor and to which thehandle is secured by screw l5.

Depending from an insulating block 42, secured to the support M, are twospring contacts [6 con- Figs. 1, 2 and 3, the actuator is mounted withina channel member 43 secured to the housing 20. Sliding movement of theactuator within the channel member is limited by suitable stops, asindicated at 33. These stops are provided by bosses on the member 43,which bosses are internally threaded to receive the screws l8. A trackmember 32 is secured to the back of the member 43 (Fig. 3) and receivesrollers 38 to be referred to later. The actuator 31 is biased toward itsFig. 2 (open-circuit) position by a pair of springs 41 the lower endsof'wh-ich are anchored on a crosspin 44 extending through the side-wallsof the channel member 43. The upper ends of springs I are anchored on across-pin 35 which extends through the actuator wings 34.

According to the present invention, the snapswitch is actuated by amember mounted for bodily, rectilineal movement relatively to the toolitself and so located as to be engaged by the hand of the operator, andmoved to switch-closing position, without special attention by theoperator, that is, as an incident of his normally grasping the handleoi. the tool and applying the tool to the work. Also, such member is soarranged as to constitute a part of the switch unit assembly.

For these purposes there is provided in this instance a grip-member 31located along the rear of the pistol-grip handle H and suitably shapedto fit the contour of the body of the handle for convenient engagementby the palm of the hand of the operator when the tool is grasped. Asindicated in Fig. l, the grip-member 3'! is located between channelwalls 45 formed integral with the handle ll. Projecting from the innerface of grip member 31 is a block 41 which carries rollers ll locatedwithin the track member 82. By reason of this construction thegripmember is movable longitudinally of, but is retained against outwardremoval from. the track member. Projecting from the block 41 is' a stud36 the outer end oi which carries the cross-pin 35, thereby connectingthe grip-member 31 to the wing portions 84 of the actuator 3|. Theactuator is thus positively operated by longitudinal movement oi thegrip-member relatively to and in the direction dictated by the trackmember.

In this preferred form oi the invention the track member is set at what,for identification, will be referred to as an acute angle to the majorlongitudinal axis. 1. e. the work-thrust axis, of the tool housing ID.More specifically, the track member may be said to be arrangedsubstantially parallel to the axis 01 the handle of the tool, whichaxis, as usual, is set at an angle to that of the tool. As the result,when the operator grasps the tool and applies a normal work thrust to itin the direction indicated in Fig. 1, the gripmember slides or rides upthe rear of the handle, in opposition to the springs II, in thedirection or motion indicated in Fig, 1 and thereby automatically throwsthe snap-switch to close the motor circuit. This condition continues,course, just so long as the operator continues to apply work thrust tothe tool. As soon as such thrust is relieved, springs ll restore thegrip-member 31 to its former position and coincidently throw thesnap-switch spring 28 to its circuit-opening position.

The described mechanism thus incorporates the combination or asnap-switch, having its own contact-actuating spring, and additionalspring-controlled means for operating the snapswitch, the spring orsprings of such additional means acting to bias the same in a directionto throw the snap-switch to its open-circuit posi tion. As will beunderstood, the bias of such additional spring (in this instance thesprings II) is sufilcient to overcome the resistance to switch-openingopposed by spring 28 when the latter is in its switch-closing osition.

It will be noted also that there is nothing critical about the extent ofmovement required of the grip-member to close the switch, any movementsuilicient to throw the snap-spring beyond its dead center positionbeing sufllcient. Nor is undue pressure required to maintain the switchclosed. As soon as the snap-spring has Passed its dead-center position,and unless the actuator is moved clear to the upper limit of its travelinto engagement with upper stop 33 (which is quite unnecessary), thethrust of the snap-spring actually opposes the switch-opening tension ofsprings 4|, with the result that the thrust necessary to maintain thewitch closed is represented simply by the necessary excess of thetension of springs 4| over the expansive force of spring 28.

Having thus set forth the nature of the invention what I claim hereinis:

1. In a portable electric tool including a housing and a motor therein,a hollow handle attached to said motor housing, said handle being set atan acute angle to the work thrust axis of the tool, a motor switchlocated within the handle, a manually operable member for operating saidswitch, said member mounted for bodily sliding movement relatively tothe handle, said movement being in a direction'substantially parallel tothe axis of said handle and therefore movable at an acute angle to thework thrust axis of the tool.

2. In a portable electric tool including a housing and a motor therein,a hollow handle'attached to said motor housing, a motor switch withinthe handle, a bodily slidable hand grip member for operating saidswitch, said member being located along the rear of the handle andshaped to the contour thereof, and track means for guiding said memberto slide at an acute angle to the work-thrust axis of the tool.

3. In a portable electric tool including a housing and a motor therein,a hollow handle attached to said motor housing, said handle being set atan acute angle tothe work thrust axis of the tool, a motor switch withinthe handle. a bodily slidable member for operating said switch, saidmember being located and arranged to form the rearwardly directed,thrust-receiving portion of the handle, and means for guiding saidmember for sliding movement at an acute angle to the direction of thrustapplied thereto.

4. In a portable electric tool including a housing and a motor therein,and a hollow handle for manipulating the tool, a motor switch controlunit bodily insertable into and removable from the handle and comprisinga switch housing and switch, means for securing the switch housing, andthereby the unit, to the handle, track means supported on the switchhousing and extending at an acute angle to the axis of the portabletool, and a manually-operable, switch controlling member mounted forbodily, sliding movement on said track means relatively to the unit andtool handle.

5. In a portable electric tool including a housing and a. motor therein,and having a hollow handle, the combination therewith of a snap-switchfor the motor mounted within the handle, said switch including acontact-actuating spring, track means within the handle set at an acuteangle to the work-thrust axis of the tool, a handgrip switch operatingmember mounted at the rear of the handle for bodily sliding movementrelatively thereto upon said track means, and spring means biased tomove said member from a closed-circuit position toward an open-circuitposition in opposition to the thrust of the contactactuating spring ofthe said snap-switch.

6. In a portable electric tool including a housing.and a, motor therein,and having a hollow handle, the combination therewith of a snapswitchfor the motor mounted within the handle, said switch including acontact-actuating spring, a hand-grip member associated with the handleand slidable on the rear thereof and relatively thereto,switch-actuating means connected to the grip member, and a second springacting to bias the switch-actuating means and grip member toward theopen-circuit position of the snap-switch,

. '5 the bias said secondspring being sufllcient to overcome theresistance to switch opening opposed by the contact-actuating spring.

.7. In a portable electric tool including a housing and a motor therein,and having a hollow handle, the combination therewith oi! a snapswitchfor the motor mounted within the handle, a hand-grip member mounted forsliding movement relatively to the handle at an acute angle to thework-thrust axis of the tool and located for engagement by the hand ofthe operator grasping the tool handle, and means responsive to suchmovement of the hand-grip member for actuating said switch.

8. In a portable electric tool including a housing and a motor therein;a hollow handle attached to "said motor, said handle being set at anacute angle to the work-thrust axis of the tool; at least one stationaryelectric contact; at least one movable electric contact; spring meansselectively movable either to a position for closing said contacts or toa position for opening said contacts; an actuator for said spring tomove said spring from either of said positions to the other I of saidpositions; a second spring for normally biasing said actuator to theposition for moving said spring to the-contact opening position; a gripmember mounted to slide along said handle in a direction of motion thatforms an acute angle to the normal thrust direction of said tool, saidgrip member being attached to said actuator, whereby, when said actuatoris biased to the contact opening position, said grip member will beretracted into inactive position, and whereby when thrust is applied tosaid handle in a direction parallel to the normal thrust direction ofsaid tool, said thrust will cause said grip member to slide along saidhandle against the bias of said second spring and thereby cause saidactuator to move to the contact closing position.

9. In a portable electric too] including a housing and a motor therein;a hollow-handle attached to said motor, said handle being set at anacute angle to the work-thrust axis of the tool; an electric switchmounted in said handle; an actuator for opening and closing said switch;a channel member supp rted in said handle and in which said actuator ismounted; a spring for normally biasing said actuator to open saidswitch; channel walls formed integral with said handle; a grip membermounted to slide along said when said actuator is biased to the positionfor opening said switch, said grip member will be retracted intoinactive position, and whereby when thrust is applied to said handle ina direction parallel to the normal thrust direction of said tool, a

component of said thrust will cause said grip member to slide along saidhandle against'the, bias of said spring and thereby cause said actu--ator to move to the position for closing said switch.

10. In a portable electric tool including a housing and a motor housedtherein; a hollow handle attached to said motor housing and set at anacute angle to the work thrust axis oi. the tool; an electric snapswitch housed in said handle and normally biased to 'an inactiveposition; an actuator formed as a part of said switch; a pair ofapertured wing portions formed integral with said actuator; a cross pin'passing through the said apertured wing portions; a threaded studpivoted on said pin between said wing portions; a pair of track memberssupported in said handle and set at an acute angle to the work thrustaxis of the tool; a plurality of rollers received in said track members;a grip member movably supported by said rollers and arranged to move ina direction parallel to the handle; and a means for securing said gripmember to said threaded'stud, whereby when said grip member is movedsaid switch is operated.

1 REYNOLD- HAPPE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

